How a Solar Pond Traps Solar Energy

The bottom zone of a pond can be used as a heat source since that zone has a concentrated salt solution with a higher temperature from absorbing solar radiation. This type of pond is called a solar pond. Solar ponds have been used to produce hot water and have good efficiency. A company wants to use this concept to generate power. Hence, a model pond is built to test its performance.

What is known:

• The size of the pond is 10m x 10m x 3m.
• The ambient air temperature is 35 ^oC.
• The temperature at the bottom of the pond is 85 ^oC.
• The salt water in the bottom layer absorbs solar radiation at the rate of 0.3 kW/m².

• Determine the maximum thermal efficiency that this power plant can have.
• Determine the maximum power generated by each m² of the bottom of the pond.

Heat Engine Works between the
Solar Pond and the Ambient Air

• The power plant is a heat engine since it generates power at the expense of heat input. Carnot heat engine has the highest thermal efficiency.
  
  η_th,rev = 1- T_L/T_H
  
  

• The thermal efficiency of a heat engine, regardless reversible or irreversible, is given by

  η_th = 1- Q_L/Q_H